Taking advantage of all available means to limit radiation exposure
is always recommended. The three methods of limiting exposure
are:
TIME
DISTANCE
SHIELDING
These methods are a part of an ALARA (As Low As Reasonably
Achievable) program.
Time
The simplest way to reduce exposure is to keep the time spent
around a radioactive source to a minimum. If time is cut in half, so
is the exposure, with all other factors remaining constant.
Distance
Distance is another effective means to reduce radiation exposure. A
formula known as the inverse square law relates the radiation
exposure rate to distance (Figure A–3). Doubling the distance from
a radiation source reduces the exposure to one-fourth its original
value. If the distance is tripled, the exposure is reduced by a factor
of nine, and so on
Figure A–3. Effect of Distance on Exposure
Appendix A–6